Lift truck with horizontally slewable load carrier

ABSTRACT

A lift truck is provided with a lift mast having a horizontal slewable load carrier. In one aspect of the lift truck the body thereof is provided with an operator&#39;&#39;s cab having a load-bearing roof onto which the load carrier can lower its load after being horizontally slewed to a laterally facing position. In another aspect of the lift truck, the fixed and movable upright guides of the lift mast are aligned longitudinally of the lift truck with the load carrier being mounted to the movable guide for vertical movement and for horizontal slewing.

United States Patent Inventors Maurice J. McIntyre Coquitlam, NewWestminister, British Columbia, Canada; John R. Newton, Salem, Oreg.App]. No. 840,758 Filed July 10, 1969 Patented Sept. 28, 1971 AssigneeSkagit Corporation Sedro Woolley, Wash.

Continuation-impart of application Ser. No. 740,707, June 27, 1968, nowabandoned.

LIFT TRUCK WITH HORIZONTALLY SLEWABLE LOAD CARRIER 4 Claims, 6 DrawingFigs. US. 214/654, 214/731, 214/730, 214/75 R Int. Cl. B66! 9/18 Fieldof Search 214/654, 1 731 [56] References Cited UNITED STATES PATENTS2,684,165 7/1954 Hill 214/654 2,748,966 6/1956 GOhl'ke 214/731 3,225,94912/1965 Erickson.. 214/731x 3,335,879 8/1967 Shaffer 2l4/654X FOREIGNPATENTS 588,910 12/1959 Canada 214/654 Primary Examiner-Gerald M.Forlenza Assistant Examiner-George F. Abraham Attorneys-Robert C. Smithand Plante, Hartz, Smith &

Thompson ABSTRACT: A lift truck is provided with a lift mast having ahorizontal slewable load carrier. in one aspect of the lift truck thebody thereof is provided with an operator's cab having a load-bearingroof onto which the load carrier can lower its load after beinghorizontally slewed to a laterally facing position. in another aspect ofthe lift truck, the fixed and movable upright guides of the lift mastare aligned longitudinally of the lift truck with the load carrier beingmounted to the movable guide for vertical movement and for horizontalslewing.

PATENTEUSEPZBIQTI v 3.608.760

' sum 1 or 5 INVENTORS mums: J. momma:

JOHN R. uzwrga ATTORNEYS SHEET 2 OF 5 FlG 2 INVENTORJ mums .1. mcmnms BYJOHN R. uewrou A T TORNEYS PATEmEnsmm SHEET 3 [IF 5 MAURICE i I E BYaoau'rm u wk ATTORNEYS m oE PATENTED SEP28 15m 3 L 6 O8 7 6 0 SHEET u[If 5 INVENTORS mums: a. MCINTYRE BY gel-m R. NEWTQ ATTORNEYS PATENTEDSEP28 I97! 3" 608,760

sum 5 [IF 5 INVENTORS MAURICE J. MclNTYRE JOHN R. NEWTON ATTORNEYS FIG==6 LIFT TRUCK WITI-I HORIZONTALLY SLEWABLE LOAD CARRIER This applicationis a continuation-in-part of a copending U.S. Pat. application entitledLift Truck with Horizontally Slewable Load Carrier," Ser. No. 740,707filed June 27, 1968, now abandoned.

This invention relates to lift trucks. More particularly, this inventionrelates to lift trucks adapted to handle large, elongated loads such asstacked lumber in restricted areas.

Life trucks designed to handle large, elongated loads have been proposedwherein a load carrier, such as a fork lift carrier, can be disposed ina forward facing position relative to the truck to pick up a load andthen slewed to a laterally facing position to place the elongated loadparallel to the truck for transport. These lift truck designs areintended to facilitate transport of elongated material along narrowaisles and yet permit front end loading and unloading. However, the loadcapacity of such lift trucks is often limited, to a maximum weight orwidth or both, by lift truck structure that cannot withstand the forcesimposed by large loads, or that unbalances the truck when the load isslewed to a laterally facing position, or that blocks the operator'slateral line of sight when the load is slewed to a laterally facingposition.

A primary object of this invention is to provide a lift truck wherein aload carrier is adapted to be horizontally slewed from a forward facingposition to a laterally facing position and to overlay the load bearingroof of an operators cab when in the laterally facing position. Anotherobject is to provide such a lift truck wherein the lift mast fixed andmovable guides are mounted by the truck body parallel with thelongitudinal axis of the body with the load carrier horizontallyslewable relative to the lift mast guides.

These and other objects and advantages of the invention will becomeapparent from the following description and the accompanying drawings ofwhich:

FIG. I is a side elevation view of a preferred embodiment of theinvention;

FIG. 2 is a front elevation view of the FIG. 1 embodiment;

FIG. 3 is a plan view in partial cross section taken along the line 3-3of FIG. 2;

FIG. 4 is a perspective view of the FIG. 1 embodiment with certaincomponents blown apart in assembly diagram form;

FIG. 5 is a front elevation view of another embodiment of the invention;and

FIG. 6 is a vertical cross section taken along the lines 6-6 of FIG. 5.

In brief, the lift truck of the present invention comprises a bodycarried by forward and rearward wheel assemblies and mounting a liftmast. The lift mast includes a first guide fixed against verticalreciprocity movement, a second movable guide mounted by the first guidefor vertical reciprocatory movement, a load carrier mounted by themovable guide for vertical reciprocity movement and adapted to behorizontally slewed, means for vertically raising and lowering themovable guide and the load carrier, and means for horizontally slewingthe load carrier.

In one aspect of the invention, the body is provided with an operator'scab having a reinforced load bearable roof, and the lift mast is soconstructed that when the load carrier is raised to an elevationexceeding that of the body cab, the load carrier and its load can beslewed to overlay the cab. Placing the load over the cab permits moreeven distribution of the load on the vehicle thereby enabling thetransport of heavier and wider loads with a greater degree of stability.In this aspect of the invention, the operator's forward line of sight isthrough the front and framework of the body, and his lateral line ofsight to both sides is completely unobstructed by the load.

In another aspect of the invention, the fixed and movable guides of thelift mast are mounted parallel with the lift truck longitudinal axis andthe load carrier is pivotally mounted to the movable guide such that itis substantially perpendicular to the stationary guide when in itsforward facing position and is substantially parallel to the fixed guidewhen in its laterally facing position. The fixed guide is preferablypivotally mounted for slight pivotal movement on a horizontal axis andmeans to pivot the fixed guide about such axis are provide to affordtilting adjustment of the load carrier when the latter is in a forwardfacing position. In this aspect of the invention, the structure of thefixed and movable guides is not mounted for horizontal slewing movementand therefore a massive vertical pivot mechanism is not required toaccomplish the required horizontal slewing of the load carrier. Thisaspect not only reduces the structural requirement of the lift mast butalso permits reduction of the size of the lift mast elements so that agreater portion of the body width can be effectively utilized toaccommodate a loaded laterally facing lift carrier with the load centerbeing maintained adequately close to the longitudinal axis of thevehicle.

Referring to the FIGS., a preferred embodiment of the lift truck of thisinvention is a rear-engine vehicle comprising a body 10, forward andrearward wheel assemblies 12 and 14 on which the body is carried, and alift mast assembly 16. The body is a low silhouette structure with aheight sufficient to accommodate the necessary head room in an operatorscab 18. The roof 20 of the cab is a reinforced structure designed tobear the weight of a load carried by the lift mast assembly. The roofstructure comprise a pair of vertical frames, each having a cutoutsection along their upper sides as shown in FIG. 4, and a plurality ofoverhead crossbars connected to and extending between the upper sides ofvertical frames. As thus structured, the cab roof constitutes a loadsupporting deck onto which the load carrier can lower its load fortransport without continued force exerted on the lift mast.

The lift mast comprises a first guide 22 that is fixed against verticalreciprocity movement, a second movable guide 24 mounted by the fixedguide for vertical reciprocity movement, a load carrier 26 mounted tothe movable guide for vertical reciprocatory movement and adapted to behorizontal slewed, means 28 for effecting vertical reciprocatorymovement of the movable guide and the load carrier, and means 30 foreffecting horizontal slewing of the load carrier. The fixed guide ismounted to one end of a horizontal crossbeam 32, which is itselfpivotally mounted to the axle housing 34 of the front wheel assemblysuch that the fixed guide can be pivoted forwardly and rearwardly abouta horizontal axis. Means 36 are provided to effect this slight pivotalmovement of the fixed guide. The fixed guide is aligned parallel withthe longitudinal axis of the lift truck and positioned adjacent to theinward of one of the front wheel sets of the front wheel assembly.

The fixed guide comprises forward and rearward upright legs, 36 and 38,brace members 48 connecting the two legs, and a crosshead 50 connectingthe top ends of the two legs. The forward leg (seen in cross section inFIG. 3) is structurally composed to provide a rearwardly opening guidechannel. The rearward leg (seen in cross section in FIG. 3) isstructurally composed to provide a main guide channel opening laterallyinward toward the opposite side of the vehicle and a secondaryforward-opening guide channel on the backwall of the main channel. Theintermediate crossbraces are rigidly connected to the outboard sides ofthe forward and rearward legs. The base member is rigidly connected tothe crossbeam 32.

The movable guide comprises forward and rearward upright legs, 44 and46, intermediate brace members 48 connecting the two legs, and a crosshead 50 connecting the top ends of the two legs. The forward leg 44 (seein cross section in FIG. 3) is structurally composed to provide aforward-opening guide channel fitted into the rearward opening guidechannel of the forward fixed guide leg 36, and a rearward opening guidechannel. The rearward leg 46 (see in cross section in FIG. 3) isstructurally composed to provide a laterally outward opening guidechannel fitted into the laterally inward opening guide channel of therearward guide leg 38, and a laterally inward opening guide channel.Sets of forward and rearward movable-guide leg roller bearings 52, 54and 55 are provided to vertically guide the movable guide legs as thelatter vertically traverse the fixed guide legs. Roller bearings 52 and54 are joumaled to the fixed guide legs and designed to track in theadjacent guide channels of movable guide legs. Roller bearings 55 arejournaled to the respective movable guide leg and designed to track inthe adjacent guide channel of the fixed guide leg. The forward rollerbearings 52 are journaled for rotation on axis aligned parallel with thelongitudinal axis of the vehicle. The rearward roller bearings 54 arejournaled for rotation on axis aligned laterally perpendicular to thelongitudinal axis of the vehicle, and the rearward roller bearings 55are journaled for rotation on axis aligned parallel with thelongitudinal axis of the vehicle.

The load carrier 26 is mounted to the movable guide by a carriage 56that is adapted to track along the movable guide. The carriage comprisesa framework 58 and a load carrier pivot mount 60. The box framework 58is provided with roller bearings 62 joumaled to the forward end sectionof the framework and designed to track in the adjacent rearward openingguide channel of the movable guide forward leg, and with roller bearings64 joumaled to the rearward end section of the framework and designed totrack in the adjacent inwardly opening guide channel of the movableguide rearward leg. The forward roller bearings are joumaled forrotation on axis aligned parallel with the vehicle, and the rearwardroller bearings are joumaled for rotation on axis aligned laterallyperpendicular to the longitudinal axis of the vehicle. The load carrierpivot mount is rigidly connected to the forward end section of theframework and extends forwardly therefrom, and is provided with pivotjoumaled mounting openings 66 top and bottom at the forward end thereofand with an opening 68 through the center thereof.

As can be seen from FIG. 3, the forward and rearward legs of the fixedand movable guides are laterally offset with the rearward legs beingslightly outboard of the forward legs. Consequently, the forward andrearward end sections of the framework are also laterally offset fromone another and are connected by askew top and bottom sections of theframework.

The load carrier 26 comprises a carrier frame 70 and a pair of liftforks 72. The carrier frame comprises a peripheral box beam frameworkwith intermediate vertical box beam braces. The frame is pivotallymounted to the forward end section of the load carrier pivot mount 60 bymeans such as a journal shaft 74. The lift forks are generally L-shapedmembers, the upper ends of which are pivotally suspended by cross rods76 mounted by the carrier frame. The lift forks extend below the carrierframe a sufficient distance to contact the driving surface when thecarriage and the carrier frame mounted thereto have been lowered totheir lowest levels.

The lift forks 72 may be positioned along their respective cross rods 76to vary the spacing between them. In FIG. a preferred means for spacingeach lift fork comprises an arcuate fork shifter member 77 pivotallyhinged to the base of carrier frame 70 at 79 for movement parallel tothe plane of the carriage frame. The upper end of member 77 is providedwith an arcuate bolt 81 designed to be engaged by a follower rod 83. Theupper end of the respective lift fork is mounted by a retainer sleeve 85which is slidably mounted on the respective cross rod 76 and whichmounts follower rod 83. One end of a hydraulic cylinder assembly 87 ispivotally mounted to the side of carrier frame 76 and the other end ispivotally mounted to the fork shifter member 77. By this arrangement,the extension and retraction of the cylinder assembly 87 will efiectlateral shifting movement of the respective lift fork, through pivotalmovement of the member.

The means 28 for effecting vertical reciprocatory movement of themovable guide and load carrier comprises a telescoping hydraulic ram 78.The base of the ram cylinder is mounted to the base member of the fixedguide. The upper end of the ramrod mounts a sheave encased in aload-bearing bracket 80, the bracket being connected to the crosshead ofthe movable guide. A chain 82 is reeved over the sheave and is attachedat one end to the upper end of the ram cylinder and at the other end tothe carriage. Thus, when the ramrod is extended the bracket 80 will liftthe movable guide in a 1:1 ration and the chain will lift the carriagein a 2:1 ratio.

The means 30 for horizontally slewing the carrier comprises a cylinderand rod assembly, one end of which is pivotally mounted to the carriageand the other end of which is pivotally mounted to the carrier frame.The cylinder conveniently extends through the opening 68 of the pivotmount. The cylinder and rod assembly has a sufficient stroke to slew thecarrier through an angle of 90 from a forward facing position to alaterally facing position.

The means 36 for effecting pivotal movement of the lift mast about thepivot points on the front axle housing comprises a hydraulic cylinderand rod assembly, one end of which is pivotally mounted to the body andthe opposite end of which is pivotally mounted to one of theintermediate brace members 40. The cylinder rod assembly has asufficient stroke to provide the lift mast with the required degree offorward and rearward tilt, which will usually be under 10.

In the operation of the lift truck of the invention, a load such aslirnber or the like can be engaged when in the FIG. 1- 2 position bydriving the lift forks underneath the load. The ram is then actuated toraise the movable guide and the carriage to elevate the carriersufficiently high to clear the cab. The cylinder rod assembly 30 thenretracts to slew the loaded carrier to its laterally facing positionshown in dotted lines in FIGS. 1-2. The ram may then be retracted tolower the caboverlaying lift fork into the cutout roof section such thatthe load will be lowered on to and supported by the cab roof structure.

When the load is engaged by the forward facing load carrier, the bendingforces imposed on the carriage are largely transferred to the lift mastguides by the rearward roller bearing sets 54 and 64. When the loadcarrier is slewed to its laterally facing position, bending movementforces, imposed on the carriage are largely transferred to the lift mastguides by the forward roller bearing sets 52 and 62. During thehorizontal slewing of the load carrier, both the above-mentioned forwardand rearward roller bearing sets experience bending movement forces.

In the event that it is desired to stabilize the load by clamping downon it when it is positioned as shown in dotted line in FIG. 2, ahydraulic clamp arm assembly 82 may be mounted along one side of thebody and generally in line with and rear ward of the lift mast fixedguide as shown in FIGS. 1, 2 and 4. This assembly comprises an uprightarm casing in which a generally L-shaped clamp arm is telescopicallypositioned, the clamping section of the arm being extended laterallytoward the opposite side of the body. A preferred load clamp assembly isshown in FIGS. 5 and 6 carried by the carrier frame 70. By mounting theclamp assembly to the carrier frame, the load may be stabilized duringlifting and slewing in addition to stabilizing the load after it hasbeen slewed to a transport position. The FIGS. 1, 2 and 4 embodiment ofclamp assembly 82 cannot function to stabilize the load until the loadis slewed to the dotted line position shown in FIG. 2.

The preferred clamp assembly 91 comprises a clamp lever arm 93 pivotallyhinged to the carrier frame 70 at 95 for movement parallel to the planeof the carrier frame. A clamp mounting arm 97 is fixedly secured to theouter end of the lever arm 93 and extends outwardly therefrom andterminates in a depending bracket 99. The clamp comprises an elongatedmounting bracket 101 pivotally hinged to bracket 99 and extendinggenerally perpendicular to the plane of the carrier frame, and anelongated, thick walled tube 103 secured to the base of bracket 101 bybolts or other suitable means. A hydraulic cylinder assembly 105 ispivotally connected at one end to the carrier frame 70 and pivotallyconnected at the other end to lever arm 93. By this arrangement, theextension and retraction of the cylinder assembly 105 will effectvertical movement of the clamp to accommodate loads of varying height.Tube 103 is fabricated from material having sufficient flexibility tomold itself to the surface confirmation of the load and also havingsufficient stiffness to transmit adequate load bearing forces to holdthe load.

In the FIGS. 5 and 6 embodiment, the carrier frame 70 is provided withupstanding extension side members 107 and 109 to provide additionalsupport for tall loads. As shown, lever arm 93 and cylinder assembly 105are pivotally secured to one of these extensions.

To minimize overloading the load carrier pivot mount, a triangularbumper plate 33 is vertically positioned at the left end of thecrossbeam 32. The vertical forward edge of the bumper plate contacts theback of the load carrier frame when the latter is being loaded.Appropriate contact members may be located on the back of the frame forcontact by the plate 33.

It is believed that the invention will have been clearly understood fromthe foregoing detailed description of my now preferred illustratedembodiment. Changes in the details of construction may be resorted towithout departing from the spirit of the invention and it is accordinglymy intention that no limitations be implied and that the hereto annexedclaims be given the broadest interpretation to which the employedlanguage fairly admits.

We claim:

1. A lift truck which comprises a body;

forward and rearward wheel assemblies on which said body is carried;

and a lift mast comprising first guide means mounted on said body in aplane generally parallel with the vertical plane containing thelongitudinal axis of said lift truck and fixed against verticalreciprocatory movement and against horizontal slewing movement, movablesecond guide means retained and vertically guided by said first guidemeans for vertical reciprocatory movement, load carrier means mounted tosaid movable guide means for vertical reciprocatory movement and adaptedto be horizontally slewed, means for effecting vertical reciprocatorymovement of said movable guide means and of said load carrier means, andmeans for horizontally slewing said load carrier means relative to saidfirst and second guide means; and a load clamp assembly mounted on saidload carrier means for movement therewith which comprises a clamp memberextending outwardly from said load carrier means and clamp-mountingmeans adjustably mounting said clamp member on said load-carrier meansfor vertical adjustment relative to said load-carrier means.

2. The lift truck of claim 1 wherein said load clamp-mounting meansincludes a clamp lever arm pivotally hinged near one side of saidload-carrier means and extending generally parallel to the front to rearaxis of said carrier,

a clamp-mounting arm secured to the outer end of said clamp lever armand extending substantially perpendicular to said lever arm,

and hydraulic motor means mounted on said load-carrier means andoperatively connected to effect vertical movement of said clamp member.

3. In the lift truck of claim 1 wherein said clamp member comprises anelongated tube pivotally mounted to said clamp mounting arm andfabricated from material having sufficient flexibility to mold itself tothe surface conformation of the load and also having sufficientstifiness to transmit adequate load-bearing forces to hold the load.

4. The lift truck of claim 2 wherein said load-carrier means includes apair of lift forks and a pair of generally horizontal cross rods, eachlift fork being suspended by one crossrod and being slidably adjustabletherein; and including a pair of lift fork-adjusting means, each suchmeans comprising a fork shift member, pivotally hinged at one end to astationery part of said load-carrier means and coupled at the oppositeend to one of said lift forks, and activating means mounted at one endon a stationery part of said load-carrier means and coupled at theopposite end to said fork shifter member to effect lateral shiftingmovement of said lift fork on said crossrod through pivotal movement ofsaid fork shifter member.

1. A lift truck which comprises a body; forward and rearward wheelassemblies on which said body is carried; and a lift mast comprisingfirst guide means mounted on said body in a plane generally parallelwith the vertical plane containing the longitudinal axis of said lifttruck and fixed against vertical reciprocatory movement and againsthorizontal slewing movement, movable second guide mEans retained andvertically guided by said first guide means for vertical reciprocatorymovement, load carrier means mounted to said movable guide means forvertical reciprocatory movement and adapted to be horizontally slewed,means for effecting vertical reciprocatory movement of said movableguide means and of said load carrier means, and means for horizontallyslewing said load carrier means relative to said first and second guidemeans; and a load clamp assembly mounted on said load carrier means formovement therewith which comprises a clamp member extending outwardlyfrom said load carrier means and clampmounting means adjustably mountingsaid clamp member on said load-carrier means for vertical adjustmentrelative to said load-carrier means.
 2. The lift truck of claim 1wherein said load clamp-mounting means includes a clamp lever armpivotally hinged near one side of said load-carrier means and extendinggenerally parallel to the front to rear axis of said carrier, aclamp-mounting arm secured to the outer end of said clamp lever arm andextending substantially perpendicular to said lever arm, and hydraulicmotor means mounted on said load-carrier means and operatively connectedto effect vertical movement of said clamp member.
 3. In the lift truckof claim 1 wherein said clamp member comprises an elongated tubepivotally mounted to said clamp mounting arm and fabricated frommaterial having sufficient flexibility to mold itself to the surfaceconformation of the load and also having sufficient stiffness totransmit adequate load-bearing forces to hold the load.
 4. The lifttruck of claim 2 wherein said load-carrier means includes a pair of liftforks and a pair of generally horizontal cross rods, each lift forkbeing suspended by one crossrod and being slidably adjustable thereon;and including a pair of lift fork-adjusting means, each such meanscomprising a fork shift member pivotally hinged at one end to astationery part of said load-carrier means and coupled at the oppositeend to one of said lift forks, and activating means mounted at one endon a stationery part of said load-carrier means and coupled at theopposite end to said fork shifter member to effect lateral shiftingmovement of said lift fork on said crossrod through pivotal movement ofsaid fork shifter member.